Seasonal fecundity and costs to λ are more strongly affected by direct than indirect predation effects across species

Ecology ◽  
2017 ◽  
Vol 98 (7) ◽  
pp. 1829-1838 ◽  
Author(s):  
Joseph A. LaManna ◽  
Thomas E. Martin
Keyword(s):  
Predation Effects ◽  
Seasonal Fecundity

Testing the potential for supplementary water to support the recovery and reintroduction of the black-footed rock-wallaby

2017 ◽  
Vol 44 (3) ◽  
pp. 269 ◽  
Author(s):  
Rebecca West ◽  
Matthew J. Ward ◽  
Wendy K. Foster ◽  
David A. Taggart
Keyword(s):  
Population Growth ◽  
Threatened Species ◽  
Population Decline ◽  
South Australia ◽  
Camera Traps ◽  
Limiting Factor ◽  
Population Growth Rates ◽  
Introduced Predators ◽  
Predation Effects

Context Supplementary resource provision is increasingly used by conservation managers to manipulate habitat conditions that limit population growth of threatened species. These methods are popular in reintroduction programs because they can assist released individuals to adapt to novel environments. In situ management and reintroductions are being used to recover warru (black-footed rock-wallaby, Petrogale lateralis MacDonnell Ranges race) on the arid Anangu Pitjantjatjara Yankunytjatjara (APY) Lands of South Australia. Direct predation by introduced predators is thought to be the main cause of population decline, but indirect predation effects reducing access to water resources has also been proposed as a limiting factor. Aims To determine whether warru would use supplementary water and so provide a tool to alleviate resource pressure for in situ (wild) and reintroduced warru populations. Methods We provided supplementary water to a wild and reintroduced warru population across 12 months. Drinking rates were calculated by monitoring water points with camera traps and modelled against plant moisture content and total rainfall. We also examined whether number of visits to water points by warru predators and competitors was significantly different to control points (no water present). Key results Wild and reintroduced warru used water points within 0–10 days of installation. No significant increase in visits by predators or competitors was observed at water points. Drinking rates were significantly higher during dry winter months (March–October) for both wild and re-introduced populations. Conclusions Supplementary water is readily utilised by warru. Water could be provided in this manner to warru populations where predators are present, particularly during drier months (generally March–October on the APY Lands), periods of drought or after fire, when food resources will have a lower water content and/or be less abundant. This may increase breeding rates and recruitment of young, and improve the probability of persistence for populations of this threatened species, and should be further investigated. Implications Supplementary water provision may be a useful tool to increase population growth rates for threatened mammalian herbivores in arid habitats. Experimental trials of the uptake of supplementary water and effects on population dynamics will provide important data for implementing adaptive management frameworks for conservation.

scholarly journals Long time horizon for adaptive management to reveal predation effects in a salmon fishery

2016 ◽  
Vol 26 (8) ◽  
pp. 2695-2707 ◽  
Author(s):  
Timothy E. Walsworth ◽  
Daniel E. Schindler
Keyword(s):  
Adaptive Management ◽  
Time Horizon ◽  
Long Time ◽  
Predation Effects ◽  
Salmon Fishery

Estimating population‐specific predation effects on Chinook salmon via data integration

2020 ◽  
Author(s):  
Mark H. Sorel ◽  
Richard W. Zabel ◽  
Devin S. Johnson ◽  
A. Michelle Wargo Rub ◽  
Sarah J. Converse
Keyword(s):  
Data Integration ◽  
Chinook Salmon ◽  
Predation Effects

scholarly journals Demography of Bell's Vireos in Missouri Grassland-Shrub Habitats

The Auk ◽  
2000 ◽  
Vol 117 (4) ◽  
pp. 925-935 ◽  
Author(s):  
Joel M. Budnik ◽  
Mark R. Ryan ◽  
Frank R. Thompson III
Keyword(s):  
Nest Predation ◽  
Molothrus Ater ◽  
Nesting Success ◽  
Growth Potential ◽  
Population Declines ◽  
Annual Survival ◽  
Rate Of Increase ◽  
Study Population ◽  
Breeding Seasons ◽  
Seasonal Fecundity

Abstract Numbers of Bell's Vireos (Vireo bellii) have declined throughout much of the breeding range in recent years, yet little information exists to determine factors that are causing these declines. We studied Bell's Vireos nesting in grassland-shrub habitats at two study areas in central Missouri to determine reproductive performance, survival, and population growth potential. Birds were color banded and observed during the breeding seasons of 1996, 1997, and 1998 to determine seasonal fecundity. We monitored 124 breeding pairs (127 pair years) and 213 nests. Density declined from 1.00 to 0.80 territories per 10 ha at the first site and increased from 1.11 to 1.33 at the second site during the study. Mean nesting success was 31 ± SE of 0.03% overall and ranged from 13 to 42% among years and study areas; 57% of the pairs fledged at least one young. Low annual production was a function of high rates of nest predation (41% of all nests observed, accounting for 44 to 78% of daily nest mortality annually) and nest parasitism by Brown-headed Cowbirds (Molothrus ater; 29% of nests observed, 17 to 37% of daily nest mortality annually). Mean seasonal fecundity was 1.60 young fledged per pair per year (range 1.00 to 1.79). Annual survival of adults was 61 ± 0.04% and was higher than previously reported. We used our estimates of seasonal fecundity and annual survival of adults to determine the finite rate of increase (λ) for our study population. Our study areas seemingly comprised sink habitats (λ = 0.85). Thus, the vireos on our study areas likely were limited by low reproductive success. Population declines also may be caused by habitat loss, which highlights the need for investigation of historical and current rates of loss of grassland-shrub habitat.

scholarly journals Coexistence of surface and cave amphipods in an ecotone environment

2011 ◽  
Vol 80 (2) ◽  
pp. 133-141 ◽  
Author(s):  
Roman Luštrik ◽  
Martin Turjak ◽  
Simona Kralj-Fišer ◽  
Cene Fišer
Keyword(s):  
Leaf Litter ◽  
Species Interactions ◽  
Interspecific Interactions ◽  
Habitat Choice ◽  
Intraspecific Interactions ◽  
Size Dependent ◽  
Predation Effects ◽  
Similar Body ◽  
Subterranean Species

Interspecific interactions between surface and subterranean species may be a key determinant for species distributions. Until now, the existence of competition (including predation) between these groups has not been tested. To assess the coexistence and potential role of interspecific interactions between surface Gammarus fossarum and subterranean Niphargus timavi, and to determine their micro distributions, we conducted a series of field and laboratory observations. We aimed to determine: (1) species substrate preference, (2) whether the presence of G. fossarum influences the habitat choice of N. timavi, and (3) possible predation effects on micro habitat choice of small juveniles. Throughout a small river in SW Slovenia, N. timavi was predominantly found in leaf litter and gravel, but rarely in sand. In the sand however, we exclusively found juveniles. In contrast, surface G. fossarum sheltered mainly in leaf litter. A similar, body size dependent, micro distribution was observed in G. fossarum, where small individuals were generally found in gravel and sand. The presence of G. fossarum affected the micro distribution of juvenile, but not adult, N. timavi. In the laboratory we observed predation and cannibalism in both species. Niphargus timavi, however, appeared to be a more efficient predator than G. fossarum. In particular, juvenile N. timavi were most vulnerable to preying by adults of both species. This probably affected the distribution of juvenile N. timavi that chose finer substrates when placed with adult individuals in an aquarium with granules of different size. To understand the distribution of subterranean species, the summed effect of intraspecific interactions, as well as surface – subterranean species interactions, in particular between individuals of different size, should be taken into account.

Distribution, abundance, and predation effects of epipelagic ctenophores and jellyfish in the western Arctic Ocean

2010 ◽  
Vol 57 (1-2) ◽  
pp. 127-135 ◽  
Author(s):  
Jennifer E. Purcell ◽  
Russell R. Hopcroft ◽  
Ksenia N. Kosobokova ◽  
Terry E. Whitledge
Keyword(s):  
Arctic Ocean ◽  
Western Arctic Ocean ◽  
Predation Effects ◽  
Western Arctic

Effects of fish predation in erosional and depositional habitats in a temperate stream

2000 ◽  
Vol 57 (7) ◽  
pp. 1369-1379 ◽  
Author(s):  
Jordan Rosenfeld
Keyword(s):  
Coho Salmon ◽  
Resource Limitation ◽  
Fish Predation ◽  
Benthic Invertebrate ◽  
Invertebrate Community ◽  
Ceramic Tiles ◽  
Organic Detritus ◽  
Predation Effects ◽  
Temperate Stream

Combined effects of predation by benthic and drift-foraging fish (prickly sculpin (Cottus asper) and coho salmon (Onchorhynchus kisutch) parr) on benthic invertebrate community and trophic structure were evaluated in Mayfly Creek, a previously fishless stream in the Coast Range Mountains of British Columbia. The role of microhabitat (substrate) in mediating predation effects was assessed by comparing invertebrate community structure on unglazed ceramic tiles and gravel baskets nested within enclosures. The role of macrohabitat was evaluated by placing enclosures in pool and riffle habitats. Effects of fish predation were most pronounced on tile substrate and in riffle habitat and least pronounced on gravel substrate in pool habitat. The presence of fish caused a decrease in abundance of larger-bodied herbivores (primarily the mayflies Ameletus and Baetis) and had positive indirect effects on algae and smaller invertebrates (primarily Orthocladiinae chironomids and nemourid stoneflies), probably through competitive release. In contrast with herbivores, detritivorous invertebrates were less influenced by fish predation and more highly correlated with the abundance of organic detritus. The distribution and abundance of detritivores in Mayfly Creek appear to be primarily influenced by bottom-up forces (implying resource limitation), while grazers in algal-based food chains are more strongly influenced by top-down effects (fish predation).

Feeding Rates, Double Brooding, Nest Reuse, and Seasonal Fecundity of Eastern Wood-Pewees in the Missouri Ozarks

2014 ◽  
Vol 126 (1) ◽  
pp. 128-133 ◽  
Author(s):  
Sarah W. Kendrick ◽  
Frank R. Thompson ◽  
Jennifer L. Reidy
Keyword(s):  
Feeding Rates ◽  
Double Brooding ◽  
Nest Reuse ◽  
Seasonal Fecundity
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